1. Field of the Invention
The present invention relates to an image capture apparatus, and in particular to an image capture apparatus for correcting an image obtained by an image sensor that has focus-detection pixels.
2. Description of the Related Art
There is known to be technology for realizing automatic focus detection by phase difference detection (phase difference AF) without using a separate phase difference detection sensor, by using a portion of the pixels configuring an image sensor as focus-detection pixels, and using the phase difference between subject images obtained from the focus-detection pixels.
For example, in Japanese Patent Laid-Open No. 2000-292686, each focus-detection pixel is given a pupil division function by being provided with a pair of photodiodes A and B at positions that are eccentric to the optical axis of the on-chip microlens. The focus-detection pixels are arranged at predetermined intervals among the imaging pixels, and image signals from the photodiodes A and B are used in phase difference AF.
Since the photodiodes of the focus-detection pixels in Japanese Patent Laid-Open No. 2000-292686 are provided at positions that are eccentric to the optical axis of the on-chip microlens, the focus-detection pixels have a different structure from the imaging pixels, whose photodiodes are provided on the optical axis. The amount of crosstalk on surrounding pixels is therefore different between the imaging pixels and the focus-detection pixels.
Japanese Patent Laid-Open No. 2009-124573 discloses technology for suppressing image quality degradation in the vicinity of the focus-detection pixels that occurs due to crosstalk from the focus-detection pixels on surrounding imaging pixels. Japanese Patent Laid-Open No. 2009-124573 proposes a method for using approximation data on the positions of surrounding focus-detection pixels to correct the influence of crosstalk from focus-detection pixels in image data from the imaging pixels.
With the above-described image capture apparatus of Japanese Patent Laid-Open No. 2009-124573, output from surrounding focus-detection pixels is used to correct the image data output from the imaging pixels. However, if a surrounding focus-detection pixel is a defective pixel, and correction is performed using its output, correction errors will appear in the imaging pixel data. Depending on the extent of the defect, it is possible for the correction to instead make the image quality worse.